Semiconductor processing systems are characterized by extremely clean environments and extremely precise semiconductor wafer movement. Industries place extensive reliance upon high-precision robotic systems to move substrates, such as semiconductor wafers, about the various processing stations within a semiconductor processing system with the requisite precision.
Reliable and efficient operation of such robotic systems depends on precise positioning, alignment, and/or parallelism of the components. Accurate wafer location minimizes the chance that a wafer may accidentally scrape against the walls of a wafer processing system. Accurate wafer location on a process pedestal in a process chamber may be required in order to optimize the yield of that process. Precise parallelism between surfaces within the semiconductor processing systems is important to ensure that minimal substrate sliding or movement during transfer from a robotic end effector to wafer carrier shelves, pre-aligner vacuum chucks, load lock elevator shelves, process chamber transfer pins and/or pedestals. When a wafer slides against a support, particles may be scraped off that cause yield loss. Misplaced or misaligned components, even on the scale of fractions of a millimeter, can impact the cooperation of the various components within the semiconductor processing system, causing reduced product yield and/or quality.
This precise positioning must be achieved in initial manufacture, and must be maintained during system use. Component positioning can be altered because of normal wear, or as a result of procedures for maintenance, repair, alteration, or replacement. Accordingly, it becomes very important to automatically measure and compensate for relatively minute positional variations in the various components of a semiconductor processing system.
In the past, attempts have been made to provide substrate-like sensors in the form of a substrate, such as a wafer, which can be moved through the semiconductor processing system to wirelessly convey information such as substrate inclination and acceleration within the semiconductor system. As used herein, “substrate-like” is intended to mean a sensor in the form of substrate such as a semiconductor wafer, a Liquid Crystal Display glass panel or reticle. Attempts have been made to provide wireless substrate-like sensors that include additional types of detectors to allow the substrate-like sensor to measure a host of internal conditions within the processing environment of the semiconductor processing system. Wireless substrate-like sensors enable measurements to be made at various points throughout the processing equipment with reduced disruption of the internal environment as well as reduced disturbance of the substrate handling mechanisms and fabrication processes (e.g.: baking, etching, physical vapor deposition, chemical vapor deposition, coating, rinsing, drying etc.). For example, the wireless substrate-like sensor does not require that a vacuum chamber be vented or pumped down; nor does it pose any higher contamination risk to an ultra-clean environment than is suffered during actual processing. The wireless substrate-like sensor form factor enables measurements of process conditions with minimal observational uncertainty.
A dire need currently exists for systems that offer the benefits of wireless substrate-like sensors while facilitating the acquisition of and compensation for information related to positional variations of components within a semiconductor processing system. Although wireless substrate-like sensors currently provide limited information such as inclination and acceleration, they do not provide the required positional information. Technicians must still make subjective judgments to adjust the relative positions of the various components within the semiconductor processing system in order to ensure that such components cooperate to provide extremely careful substrate processing. Currently available sensors do not enable automatic adjustment of positional offsets between components of a semiconductor processing system.